Proportional flow divider



April 20, 1965 2 Sheets-Sheet 1 Filed May 24, 1963 PII 20, 1965 R. w.ERICKSON ETAL 3,179,120

PROPORTIONAL FLOW DIVIDER 2 Sheets-Sheet 2 Filed May 24, 1963 UnitedStates Patent O 3,179,120 PRUPGRTIONAL FLOW DIVlDER Robert W. Ericksonand John F. Lindell, Newton, Iowa, assignors to- Koeln-ing Company,Milwaukee, Wis., a corporation of Wisconsin Filed May 24, 1963, Ser. No.282,953 1 Claim. (Cl. 137-161) This invention relates generally to atractor mounted material loader of the type including a verticallyswingable boom having a material handling bucket at the outer end of theboom.

In loaders of this type it is necessary that the boom and bucketmovements are properly coordinated under various operating conditions,and this is usually accomplished by means of hydraulic cylinders and anassociated hydraulic control system for the cylinders.

One of the important functions which are required of such a controlsystem in the operation of the loader is to keep -the bucket level andthereby prevent an accumulated load therein from spilling while the boomand bucket are swung up and down in unison relative to the ground.

The principal object of the present invention is to provide an improvedproportional ow divider which lends itself for use in a hydrauliccontrol system of the mentioned character and by means of which thedesired leveling of the bucket will be effected automatically while theboom is moved up or down from one vertically adjusted position toanother.

More specilically it is an object of the present invention to provide animproved proportionalow divider of the mentioned character incorporatinga check valve which in association with other circuit components willcontrol operation of the boom lift cylinder as well as of the buckettilt cylinder.

These and other objects and advantages will appear hereinafter as thisdisclosure progresses, reference being had to the accompanying drawing,in which:

FIGURE 1 shows a tractor mounted loader which utilizes the presentinvention, the view being more or less schematic in nature in regard tothe hydraulic circuit and valves; and

FIGURE 2 is a more simpliiied schematic diagram of lthe circuit shown inFIGURE 1.

Referring to the general organization shown in the drawings, 4thetractor T has a pair of lift arms 1 pivoted about a horizontal axis 1aat their rear ends. A bucket B is pivoted about a horizontal axis 2 toand between the free ends of the lift arms or booms 1.

Double acting, hydraulic lift cylinders 3 (one shown) are pivotallyconnected between the tractor and the lift arms to vertically positionthe latter, and second double acting hydraulic cylinders 4 (one shown)are connected between the bucket and the boom to tilt the bucketrelative to the arms.

A standard two-spool, four-way control valve V is mounted on the tractorand has a lift cylinder spool 6 yand a bucket tilting spool 7, both ofwhich are axially shiftable by the operator, to connect the cylinders aswill more fully appear with a hydraulic pump (not shown) but whichfurnishes pressure fluid to inlet port 8 of the control valve. An outletport 9 of the valve V dumps the low pressure fluid back to the tank 1l)via conduit 11.

. The general system also includes a normally closed, pilot operatedload check valve 14 which opens when pressure of a sutlicient amount isapplied to the pilot passage 15. The spool 16 of valve 14 is subjectedat its right end, as viewed in the drawing, to pressure from pilotpassage 15, while the other end of the spool is open `to simply drainleakage of iluid to the tank via drain conduit`2l. A manual adjustingscrew Ztl is provided for changing the resilient loading of the spring20a on the spool 16.

Excessive pressure in passage 15 passes through cross bores 15a andshifts the spool to the left. This movement permits fluid from conduit17 to ow into passage 18 via annular groove 19, and then to conduit 22,as will more fully appear.

If no pressure is applied to pilot passage 1S, then fluid flow fromconduit 17 is blocked from passage 1S and conduit 22.

A conduit 22 then places passages 1S and 1S in communication with thehead end of bucket cylinder 4 and with conduit 23 which in turncommunicates with the bucket spool portion of the control valve V.Another conduit 25 places the conduit 17 and valve: V in iluidcommunication with the -rod end of cylinder ffl.

Adjustable liow proportoner or self-leveling vulve An adjustable flowproportioning or self-leveling valve 30 is provided in the hydraulicsystem and is constructed as follows. A cylindrical valve chamber Sliwithin a housing is closed at its opposite ends by plugs 51 and S2. Thevalve chamber presents end lands 37C, 37d, and intermediate lands 37e,37j spaced axially from each other and from the end lands in the spacebetween the latter. A central fluid passage 53 extends transversely ofthe valve chamber between the intermediate lands 37e, 37f andcommunicates with a fluid inlet port 54 of the housing. A first lluidoutlet passage 55 and a second iluid outlet passage 56 extendtransversely ofthe valve chamber at the axially opposite sides,respectively, of the central tluid passage 53 intermediate the end lands37C, 37d, and; terminate at a iirst fluid outlet port 31 and at asecond,`

fluid outlet port 34, respectively, of the housing. An

axially shiftable valve spool 37 within the valve chamber Sii has aradially recessed central portion presenting an external groove G withinthe central passage 53. Thespool 37 also has axially recessed iirst andsecond end portions 57, 58 in sliding engagement, respectively with theend lands 37e and 37d. An internal passage of the valve spool 37connects the external groove G with the interior of the rst axiallyrecessed end portion 57 and presents a iiow restricting orifice 33. Aiirst branch passage 59 within the housing connects the central passage53 with the end of the valve chamber Sil which communicates with thesecond axially recessed spool end 58.

An adjustable flow restrictor 39 withinthe branch passage` 59 has avariable orifice 41. A second branch passage 60A connects the centralpassage 53 with the lirst outlet passage 55; and a check valve 36 withinthe second branch passage 6u is biased to accommodate fluid flow throughthe second branch passage 60 in the direction from the first outletpassage 55 into the central passage 53 and to when the lift cylinderspool 6 is shifted to the appropriate position, as will appear.

The function of the valve 36 is to divide the flow into two streams in aiixed proportion. relatively constant at different flow rates.

Assume valve 30 is set to divide the flow between conduits 33 and 32 inthe order of 9% and 91%, respectively.

Any flow into the valve 30 from line 35 iiows into the inlet of thevalve, and some oil then tends to go through the fixed orifice 33 to the91% port.

The variable orifice can be adjusted to provide the desired pressuredrop across itself. The adjusted pressure Patented Apr. 20, 1965 Thisproportion is` drop provides the desired drop in relation to the dropacross the lixed orice. These two different pressures on different endsof the spool 37 cause the spool `to shift and either open or closedepending on the setting. This shift ing causes the spool to meterthrough the cross holes 37a or 37b that are drilled toward the outerends of the spool.

The setting of the adjustable oritice thereby determines the ratio thatthe llow is split into.

Whenever oil is owing from line 35 through the proportion v-alve 30, andeither line 32 or 33 become shut off by a cylinder so they can accept nooil, the flow to both lines is shut olr". Assume oil is flowing and thebucket cylinder 4 becomes extended and thereby line 33 will laccept nomore oil. At the instant the cylinder stops, the pressure in the leftside or adjusted portion et the valve will rise to the same pressure asthat of the inlet. This pressure on the left end of the spool wouldcause it to shift'to the right and thereby shut olf the ilow to line 32because the cross holes 37a in the right end of the spool would becovered by the land 37C at the right side of the body. The process wouldbe exactly the same if line 32 became blocked, only the spool wouldshift to the left to cut off flow to line 33.

Oil can ow in reverse from line 32 back to line 35 because of the checkvalve 36. When oil is owing out of line 32v to line 35 via check valve36, a slight back pressure in line 32 will keep oil from coming fromline 33 out into the inlet or line 35. The only way it would be possibleto get reverse flow from 33 to 35 would be if there was a pressure inthe rod end of the bucket cylinder to pressurize line 33. This is neverthe case so no reverse flow results.

If line 33 is pressurized by an external force when no reverse ow existsfrom line 32 to line 35, oil from line 33 cannot pass into line 32. Assoon as the pressure rises in line 33, the spool 37 shifts to the rightand the cross holes on the right end of the spool seal lines 35 and 33from line 32.

The circuit also includes a conduit i2 which places the rod end ofcylinder 3 in communication with the lift spool portion of control valveV.

It should be understood that the pilot operated load check valve 14 andthe flow proportioning valve could be incorporated in the same housingor sandwiched or stacked together.

The operation of the circuit will now be described in greater detail andin reference to both standard operating functions as well yas specialoperating functions. The terms lluid or oil will be usedinterchangeably, it being understood that the invention is usable withany iluid medium as a pressure producing medium.

Raising lift arms In order to raise the lift arms 1, the spool 6 ispulled to admitlluid via conduit 35 to the proportioning valve 30. Theadjustment lll of thevvalve 3@ is set as previously mentioned, forexample, to divide the flow between conduits 33 and 32 in the order of9% and 91%, respectively. Of course, this ratio of tlow is adjustableaccording to the particular loader on which the invention is used. Atany rate, in the present example, 91% of the pressure uid passes throughthe annular groove G of the spool and is conducted by conduit 32 to theyanchor end of cylinder 3 to raise the lift arms. The fluid from t-heopposite -rod end of cylinder 3 then lloWs via conduit 42 and throughvalve V to the tank. At the same time, Huid from conduit 35 is preventedfrom flowing directly through the proportioning valve 30 because of theoneway check valve 36.

As the lift arms are raising, 9% of the fluid is conducted via conduits33 and 22 which connect with conduit 23 and the lluid llows into theanchor end of cylinder 4. At this time, fluid is trapped in the rod endof cylinder 4 by the pilot operated load check valve 14. The

4f pressure rise of this trapped fluid in the rod end of cylinder 4causes a pressure rise in conduit 22 which in turn is reflected in pilotpassage 15, thereby causing the check spool 16 to open slightly,permitting fluid llow from line 17, through check valve 14 and outpassage 18, and conduit 22 and then to the anchor end of cylinder 4.

This will cause the bucket B to dump a predetermined amount in relationto the rise of the lift arms, in accordance with the amount orproportion of lluid that is bypassed by the proportioning valve 30.

The lluid entering passage 15 from conduit 33 controls the speed of theself-leveling because this rluid is required to causethe pressure buildup in conduit 22.

It the bucket is heavily loaded, fluid would tend to be forced outconduit 17, but this is prevented because the load check valve 14El isnot open until a pressure is created in conduit 22.

The above-mentioned opening and closing of load check valve 143- is acontinuous metering operation as contrasted with a definite stop andstart operation; as a result, theV To effect dumping of the bucket, thebucket spool 7 is pushed to cause tluid to beradmitted to conduit 23andsirnultaneously permits lluid to return to the tank via con.

duit 25.

When conduit 23 is pressurized, conduit 22 is also pressurized, the loadcheck valve 14 can open but no flow occurs because of check valve 24 inconduit 17; therefore, fluid returns tothe tank through line 25 and viapassage 25a of Valve V. Fluid is prevented from leaving via conduit 33by the proportioning valve 3u which is so designed that lluid cannotflow from conduit 33 back'into conduit 32 or 35.

Bucket retracling To retract the bucket B, the operator pulls bucketspool '7 of the control valve V, causing lluid to tlow into line 25 tothe rod end of bucket cylinder 4 andallows fluid to tlow out of theanchor end through line 23 to the tank 1li. Any pressure created in line25 will-carry over to the pilot operated load check 14, via line 17. Oilfrom line 17 cannot get into passage 13 because line 22 and 23 are opento the tank, so the pilot operated load check 14 in turn would beclosed.

Lowering lift arms To lower the lift arms l, the operator pushes thelift spool 6 on the control valve V. This causes fluid to flow into line42 and open line 35 to the tank. Oil then lows out of the anchor end ofthe lift cylinder 3 through line 32 and through the check valve 36 andinto line 35 to the tank. Oil cannot get into line 35 from line 33 dueto the design of the proportion valve 39.'

Simultaneous pushing of both spools In the event both spools are pushedat the same time, the cylinder which requires least pressure willbe'actuated first, and this depends on the particular loading on themachine at that particular time. inder to move has completed itsoperation, then the other will be actuated.

Simultaneous pulling of both spools If the bucket cylinder 4 needs themost pressure, the lift cylinder 3 would move and 9% of the l'luid wouldthen go to line 22 and return to the tank, as line 23 would be open tothe tank. At the same time, there would be a After the first cyl-Vpressure in the rod end of the bucket cylinder 4 equal to the pressurein line 35 because they are both at pump supply pressure or open to acommon supply. The bucket B in this instance could possibly dump alittle if the lift cylinder 3 was able to force the iiuid back out ofline 25 into the pump supply. This would have a slight regenerativeeltect on the lift cylinder 3 and might cause it to speed up slightly.

If the lift cylinder 3 needed the most pressure, the bucket B wouldretract as in the normal bucket retract operation. Line 25 would bepressurized in this instance and thereby line 17 also. However, thepilot operated load check valve 14 would shut ott line 17, because line22 would be at low pressure due to the fact that it is open to the tankthrough line 23.

It both cylinders needed the same pressure, some fluid would be cominginto line 35 and some into line 25. In that case (in the examplementioned), 9% of the oil from line 35 would then pass to line 33 and tothe tank at low pressure `via line 22 which connects to line 23 that isopen to the tank. Any fluid that would be entering line 25 at the sametime would cause the bucket to roll back (counterclockwise), because oilfrom line 25 could not pass the pilot operated load check valve 14,because line 22 is then at low pressure and the load check valve 14closed.

Pushing both spools If the bucket cylinder 4 requires more pressure, thelift cylinder 3 will move rst. Conduits 23 and 42 will be pressurized bythe control valve spool movement. The arms 1 will lower as in a standardlowering lift arm operation. Line 22 will also be pressurized, but no oWwill occur either to line 33 or 17 due to the proportioner valve 36 andcheck valve 24. If the lift cylinder 3 needs more pressure, the bucketcylinder 4 will dump the bucket because line 25 is open to the tank, andthe pressure in lines 23 and 22 cannot be relieved because of theproportion valve 30 and check valve 24. If both cylinders need about thesame pressure, the lift arms will lower and the bucket will dump to someextent, but both actions will happen at a slower rate.

Pulling lift spool und pushing bucket spool If this spool action takesplace, and the lift cylinder needs more pressure, the bucket will dumpas in normal operation. The pressure in line 23 and 22 will bemaintained because of the check valve 24. If the bucket cylinder needsthe pressure, the lift arms will rise and 9% of the oil from line 35will go to line 33 and from there to line 22. The pilot operated check14 may open, but no flow from line 22 to line 17 would occur because ofthe check valve 24. The oil from line 22 would go to the anchor end ofthe bucket cylinder, and the bucket will dump as the arms rise.

If the bucket for some reason could not dump, the oil from line 22 Wouldget back into line 23 from line 22 and regenerate back into the controlvalve V and from there again to line 35.

If both operations need the same pressure, the lift arms would raise andthe bucket would dump, but the dumping action would be slower becausethere may not be a regenerative etlect of the tluid ilowing from line 17back into line 22 and from there to the anchor end of the bucketcylinder, because conduit 25 is open to the tank, and the oil from therod end of the bucket cylinder would return to the tank.

Pushing lift spool und pulling bucket spool It the bucket cylinder needsthe pressure, the lift cylinder will move and lines 42 and 25 will bepressurized. This will cause the lift arms 1 to lower with oil going outof line 32, check valve 36 and conduit 35.

If the lift remains stationary, the pressure in line 25 will cause thebucket to roll back. Line 17 would be pressurized in this instance also,but the oil would not go through the pilot operated load check valve 14because line 22 is at low pressure along with line 23 which is open tothe tank.

If both units moved together, the lift arms 1 would lower and the bucketwould roll back simultaneously.

A vertical upward force on the lip of the bucket with the arm stationaryIn this instance, a pressure would be induced in the rod end of the liftcylinder, but it would not move because the lift spool of the controlvalve has the `ports blocked. A pressure would also be induced in theanchor end of the bucket cylinder, and this would also be blocked by thevalve bucket spool 7. The pressure in line 23, however, will carry overto line 22, and this would cause the pilot operated load check Vvalve 14to open, but any flow through it would be prevented by the check valve24.

A vertical downward force on the lip of the bucket with the armsstationary A force on the bucket lip causes an induced pressure in theanchor end of the lift cylinder. This pressure is blocked by the liftspool 6, and also by the proportion valve 30 which prevents flow out ofline 33 unless there is ilow from line 35 to line 32. Pressure will alsobe induced in the rod end of the bucket cylinder 4, and this is blockedby the bucket cylinder spool of the control valve. This pressure alsocarries over to line 17 but tlow is stopped by the pilot operated loadcheck valve 14 which would be closed because there would be no pressurein line 22.

Lifting lurms with bucket cylinders fully extended y In this instance,line 35 would be pressurized. Thel division of flow would be 91% to line32 and 9% to line 33. Line 33 could accept no oil because it isconnected to line 22 which in turn is connected to the anchor end of.the bucket cylinders. The bucket cylinders would not move because theywere already extended. In this case, due to the proportion valve 30, owwould stop. When all the flow stops it would be necessary to retract thebucket cylinders before the lift arms could be raised.

Recupitulution By means of the present invention, an adjustable, owproportioner valve has been provided in a hydraulic systern for aself-leveling bucket type loader, by means of which the bucket isautomatically maintained in a level position as the lift arms areraised. This is accomplished without the need of special mechanicallinkages, special sets of properly proportioned hydraulic rams forvarious types and sizes of loaders, and with special series valves orslave cylinders. At the same time, an easily operated and highlyversatile control system is provided which functions in an efficientmanner. The system is foolproof in operation, easy to service, andadjust, and is capable of adaptation to loaders of existing designwithout appreciable modiiication thereto.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claim particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention:

We claim:

In a proportional ilow divider, the combination of a housing having acylindrical valve chamber presenting a pair of axially spaced annularend lands and a pair of intermediate lands spaced axially from eachother and from said end lands in the space between the latter; a centralfluid passage extending transversely of said valve chamber between saidintermediate lands and communieating with a fluid inlet port of saidhousing; a rst and a second uid outlet passage extending transversely ofsaid valve chamber at the axially opposite sides, respectively, of saidcentral uid passage intermediate said end lands and terminating at firstand second outlet ports of said housing; an axially shiftable valvespool within said valve chamber having a radially recessed vcentralportion presenting an external annular groove Within said centralpassage, axially recessed first and second end portions in slidingengagement, respectively with said end lands, and an internal passageconnecting said external groove with the interior of said first axiallyrecessed end portion and presenting a ilow restricting orifice; a firstbranch passage Within said housing connecting said central passage Withthe end of said valve chamber communicating With said second axiallyrecessed end portion of said valve spool; an adjustable ow restrictorWithin said first branch passage lhaving a variable orice; va secondbranch passage conthrough said second branch passage in the oppositedirection; said axially recessed end portions of said valve spool havingradial apertures in cooperative relation with said end lands,respectively, so Vas to proportion the ow of tluid from said centralpassage into said outlet passages by axial shifting of said valve spoolwithin said valve chamber.

References Cited b'y the Examiner UNITED STATES PATENTS M. CARY NELSON,Primary Examiner.

